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Chapter 18 G.1 Ecology and Conservation
Definitions *Community: a group of populations living together and interacting with each other in an area (ex. sand dune, pond, oak, redwood forest) affected by abiotic (non-living) and biotic (living) factors *Biosphere: all parts of the earth where organisms live divided into seven biomes 2 strategies for survival *r-strategy - huge numbers of offspring are left to fend for themselves *K-strategy - few offspring are carefully nurtured Factors affecting the distribution of plant species *temperature and water *light *soil pH *salinity *mineral nutrients Factors affecting distribution of animal species *temperature and water *breeding sites *food supply *territory Random sampling The quadrat method - organisms within the quadrat are counted and these counts are used to determine the population size 1) Map the entire area 2) Determine the size of the quadrats 3) Place a grid with numbers over the map 4) Choose which quadrats to sample using a random number table 5) Count the number of each species in each sample quadrat 6) Calculate the average number of each species in the sample quadrats 7) Multiply the average number of each species by the total number of quadrats on the map to get an estimate of the number of each species in the area The transect method - used for studying how the distribution of plants in an ecosystem is affected by abiotic factors 1) At right angles, lay a tape line along the area 2) Every 10 to 20 metres along the tape, mark out a quadrat always using the same size 3) Identify and count the plant species of interest in each quadrat 4) Measure the chosen abiotic factor in each quadrat 5) Determine the pattern of distribution of plant species in the area to see if it correlaes with the chosen abiotic factor The niche concept *niche: an organism's particular role in an ecosystem which includes fundamental niche - the potential mode of existence, given the adaptations of the species realized niche - the actual mode of existence, resulting from the adaptations and competition with other species An organism's niche includes its... #spatial habitat #feeding activites #interactions with other species Competition - when 2 species rely on the same limited resource, one species will be better adapted than the other to benefit from the resource Herbivory - a primary consumer feeding on a producer Predation - a consumer eating another consumer Parasitism - an organism lives on or in a host and depends on the host for food for at least part of its life cycle (host is harmed by parasite) Mutualism - 2 species living together where both organisms benefit from the relationship Competitive exclusion *principle that no 2 species in a community can occupy the same niche because when they have a similar need for the same resources, one will be excluded (die out) and the other will survive Biomass *the total mass of organic matter (dry mass of organic matter of living organisms, expressed in grams per metre squared per year) #Measure the total area of the ecosystem #Divide the ecosystem into small areas #Choose one plot to sample #Measure the size of each plant species. Cut down all the trees and vegetation on that plot. #Dry all the plant samples in a circulating drying oven #Use a mathematical model to show the relationship between weight and height of each plant species and its biomass #Sample other plots by measuring height and size of plants #Set traps in the plot for the animals and weigh and measure the organisms caught, using tables to determine their biomass #Average the data for all species per plot #Multiply the average per plot by the number of plots in the ecosystem to discover the biomass of the entire ecosystem #Repeat this procedure seasonally or yearly to study changes of the biomass in a forest community over time